The symptoms of senility of the skin, that is, the wrinkles formed on the skin generally relate to collagen in the dermis, which is the layer below the epidermis.
The dermis has about 0.7 mm to 4 mm thickness and is several times thicker than the epidermis. The senility of the skin is caused by the fact that the amount of collagen in the dermis is gradually reduced, thus drying the skin and forming wrinkles on the skin.
To retard the senility of the skin or to remove the wrinkles from the skin, it is required to continuously fill up a deficiency of collagen or to supply new collagen to the skin. In the related art, to accomplish the object, nutritive elements, such as Vitamin C or peptide required to produce collagen, are applied or sprayed onto the skin.
However, the above-mentioned method in which the nutritive elements, such as Vitamin C or peptide, are applied or sprayed onto the skin is problematic in that 99.7% of the applied or sprayed nutritive elements cannot pass through the stratum corneum, which is the outermost layer of the skin, but remain on the skin and finally disappear, and only 0.3% of the applied or sprayed nutritive elements can infiltrate into the dermis, so that the method is inefficient.
In an effort to overcome the problems, a skin stimulator (so-called “microneedle”) has been proposed and used. The skin stimulator is provided with sharp needles, which stimulate the skin and form a microchannel in the skin, thus supplying nutritive elements, such as Vitamin or peptide required to produce collagen, to the dermis of the skin and making the collagen be efficiently produced in the dermis.
An example of the skin stimulators may be referred to Korean Utility Model Registration No. 20-395359 (entitled a microneedle roller). As disclosed in the official gazette (Publication of Correction), the microneedle roller comprises a roller, which is formed by layering at least one circular disc, and at least one microneedle, which is formed in the circular disc or on a surface of the circular disc such that the microneedle can be exposed outside the outer surface of the roller.
The production or supplement of collagen in the dermis by stimulating the skin using the microneedles (sharp needles) of the roller can be realized with the following theory.
That is, when the skin is compressed using sharp needles, a microchannel can be formed in the skin tissue.
In the above state, when the skin tissue gets a microwound by the microneedles, new tissue can be formed in the microwound due to the natural healing force of the skin, so that the wounded skin tissue can revive as resilient new tissue.
Further, the revival of the resilient new skin tissue must be accompanied by the recovery of collagen in the dermis due to the natural healing force curing the wounded skin, thus realizing the production and supplement of collagen.
However, the above-mentioned conventional skin stimulator is problematic as follows due to the structure thereof.
In the skin stimulator, the needles must be securely inserted into respective holes formed in the circular disc one by one, so that the productivity of the skin stimulator is reduced, thereby increasing the production cost and reducing economic efficiency of the skin stimulator.
Further, it is almost impossible to securely or closely assemble the circular discs with each other such that the discs are not undesirably moved, so that the conventional skin stimulator cannot effectively stimulate the skin and the needles may be broken at the tips thereof. Further, the broken tips of the needles may cause severe injuries in the skin tissue.
Further, the needles used in the conventional skin stimulator are thin, long needles having a circular cross-section, so that, when pricking the skin with the needles, the needles pass through pain spots in the body, thus making a user feel a pain.